Complex oxide surfaces studied at the atomic scale by non-contact AFM/STM and DFT

The majority of solid state matter naturally appears in the form of an oxide, which are highly stable in atmospheric conditions, and therefore constitute a vast research area on a broad range of their properties.
I will present results obtained on two representative materials: The model binary oxide rutile TiO2(110) and the prototypical perovskite oxide SrTiO3(001) oxide. Both were studied at the atomic scale at low temperatures in ultrahigh vacuum using combined non-contact atomic force microscopy (nc-AFM) / scanning tunneling microscopy (STM) experimental setup, and the results were directly compared to density functional theory (DFT) theoretical modeling.
Rutile TiO2(110) interacts with the small O2 [1] and CO [2] gas molecules by altering its polaronic ground state. A bulk-terminated SrTiO3(001) surface can be obtained only through ferroelectricity-assisted cleaving in ultrahigh vacuum [3,4], which proved as a promising physical system for further investigations. In addition to the underlying physics and chemistry that give rise to these phenomena, I will introduce the techniques and discuss recent advances in the applied experimental and theoretical methodologies.

References:

[1] I. Sokolović, M. Reticcioli, et al. “Resolving the adsorption of molecular O2 on the rutile TiO2(110) surface by noncontact atomic force microscopy.” Proceedings of the National Academy of Sciences 117, 14827 (2020)
[2] M. Reticcioli, I. Sokolović, et al. “Interplay between adsorbates and polarons: CO on rutile TiO2(110).” Physical Review Letters 122, 016805 (2019)
[3] I. Sokolović, M. Schmid, et al. “Incipient ferroelectricity: A route towards bulk-terminated SrTiO3.” Physical Review Materials 3, 034407 (2019)
[4] I. Sokolović, G. Franceschi, et al. “Quest for a pristine unreconstructed SrTiO3(001) surface: An atomically resolved study via noncontact atomic force microscopy.” Physical Review B 103, L241406 (2021)